The fire was first reported off the side of the highway on Morgan Canyon Road near Thimbleberry Lane shortly after 3:00 am.
The highway reopened shortly after 6:00 am.
Several fire crews were working to put out the flames, which have scorched about an acre. The fire was last reported to be 30% contained.
"We had a structure threat initially, but that structure threat has been mitigated, and no longer exists," said CAL FIRE Battalion Chief Jesse Torres.
Fire officials say the steep canyon makes the firefight difficult, and they are concerned about winds later in the day.
Investigators are currently working to determine the cause of the fire and another blaze that sparked around the same time, about two miles west on Morgan Canyon Road.
This is a developing breaking news story. Stay with us for updates.